Caption: Frog thigh bone. Light micrograph of a section through the thigh of the hind leg of a common frog (Rana temporaria). The epidermis of the skin is red. Beneath it, in the dermis, are glands that secrete mucus to keep the skin moist, and chromatophores (pigment cells, black) that can contract and expand to change the colour of the frog. Poison glands (red and orange spheres) are seen below the dermis. The femur (thigh bone) is at centre right, it has been decalcified prior to imaging. Magnification: x10 when printed at 10 centimetres wide.